Although nerve growth factor, NGF, derived from the mouse salivary gland (7S-NGF), has been studied extensively, relatively little is known about the biological and biochemical properties of NGF produced outside of this gland. Recent work has established that a variety of cell types in culture synthesize NGF. Furthermore, the NGF produced by a mouse fibroblast cell line, L-cell, has several biochemical properties which are quite different from the salivary protein, 7S-NGF. One of the overall aims of this proposal is to further characterize, both chemically and biologically, L cell NGF. Radioimmunological, biochemical, and enzymatic techniques will be used to determine whether L cells synthesize 7S-NGF. In addition these cells will be examined by radioimmune and biological assay to establish if they also make a related protein, epidermal growth factor, EGF. For comparison, NGF will also be investigated in another non-salivary source, guinea pig prostate, in which NGF has recently been detected but not fully characterized. Whether or not the prostate also contains EGF will be determined. Using a cell-free translation system directed with L cell RNA, the molecular structure and function of NGF precursor molecule(s) will be studied. The processing of the precursor by the gamma subunits of 7S-NGF, a proteolytic enzyme believed to be involved in the cleavage of NGF precursor molecules, will be examined. Furthermore, the biological activity of the NGF precursor molecule(s) will be investigated. The possibility that NGF and EGF share a common precursor will also be explored. These studies may establish a useful model which may have general applicability to the processing of other protein precursors, particularly insulin to which NGF is structurally related.